1. Technical Field
The present invention relates to communication systems wherein users communicate amongst themselves utilizing information terminals on a network carrying a plurality of communication means. More specifically, among such communication systems, it relates to a communication system wherein users can select communication means ahead of initiating communication.
2. Description of Related Art
In recent years, various types of communication means have been installed in information terminals on networks: telephone functions, email devices, instant messaging devices. Examples of this sort of information terminal include, for example, the PC (personal computer), WS (work station), portable telephones, and portable information terminals used in PHS (Japan's personal handy-phone system, comparable to PCS, personal communications service in the United States). When communication is called for, users make use of the various types of communication means to suit their situations, circumstances or preferences.
Given this situation, when requesting communication it is necessary to consider the status or circumstances of the party from which communication is requested, not just the party requesting communication. In Laid-Open Patent Application 1995-250132 and Laid-Open Patent Application 1996-140158 a user registers the communication means he himself uses in advance. When a user requests communication with another user, notification occurs as to whether or not it is possible to communicate with a communication means registered by the other user.
Also, Laid-Open Patent Application 1998-55492 provides technology whereby a communication means usage possibility indication is dynamically modified according to changes in the communication means that a party can use, and before communication begins the party is notified of usable communication means. In this invention each user registers usable communication means for specified statuses in advance. Communication means usable by the user who is designated the communication destination (simply “destination user” hereinafter) are reported to the party requesting communication in accordance with that user's status.
All of the foregoing art displays only the destination user's usable communication means. Therefore the user who is sending a communication request (simply “source user” hereinafter) to someone must search the other party's usable communication means for communication means which he himself can use. This puts a heavy burden on the user in matching the other party's circumstances when he wants to communicate, and is troublesome and inconvenient for the user. Also, the destination user's usable communication means are not necessarily those that the source user can simultaneously use.
On the other hand, when the destination user does not have the communication means that the source user wants to use, if the destination user does not download the communication means from a communication means provider, communication through that communication means cannot occur. Therefore the source user must use other communication means and ask the destination user to install the desired communication means and have the destination user report completion of the installation. Expanding communication means when one wants to start communicating places a great burden on the user and interferes with smooth communication.
In addition, in recent years there have been many cases in which one user uses a plurality of user terminals and uses a plurality of terminals to suit the user's status. For example, a portable terminal is used while on the go, and different computers are used at the office and home. Under these conditions, even if it is known that a communication means can or cannot be used at one terminal, if the same sort of information is not known for the communication means at another terminal it is difficult to perform communication that takes into account the other party's status.